This Function will Test a Null Value.
First we need to make a table with required fields into a database named ‘dbase’ within the reference of MySql(Php MyAdmin).first we need to import all the require packages from the java library. Then we will make a class named ‘MySqlISNULLFunction’ which extends ‘HttpServlet’. After then we define serviceMethod() which will bring the request from doGet()method for Output. Then we need to declare all the required Drivers for Database linking. Next move will be to declare mandatory variables for accessing the database like Connection variable this variable will make a bridge or link between database and actual code within the help of drivers. The next variable will be the resultSet this will be use to fetch value from the required columns and rows. And the preparedStatement will does the job as it will use to execute the Query like executeQuery() as (SELECT 2 IS NULL). And in the end the whole criteria goes to doGet()method which will help to getting output on the web browser.
i Use ‘HTML’ code and some tags which will show the output in tabular form on the web browser.
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MySqlISNULLFunction extends HttpServlet
{
public void service(HttpServletRequest rq, HttpServletResponse rp)throws IOException, ServletException
{
rp.setContentType("text/html");
PrintWriter disp = rp.getWriter();
String driver = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql://localhost/dbase";
String uid = "root";
String psw = "root";
Connection con=null;
PreparedStatement ps = null;
ResultSet rs;
try
{
Class.forName(driver);
con = DriverManager.getConnection(url,uid,psw);
ps=con.prepareStatement("SELECT 2 IS NULL");
rs = ps.executeQuery();
String title = "Using IS NULL() Function";
String docType ="<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
disp.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" +
"<body bgcolor=\"#f4efef\">\n" + "<h1 align=\"center\">" + title + "</h1>\n" + "<ul>\n" +
"<table width=\"50%\" border=\"1\" align=\"center\">\n" + "<th>Value</th>\n"+ "</body> </html>");
while(rs.next())
{
String val = rs.getString(1);
disp.println("<tr><td align=\"center\">" + val +"</td></tr>" );
}
}
catch(Exception e)
{
e.printStackTrace();
}
disp.close();
}
public void doPost(HttpServletRequest rq,HttpServletResponse rp)throws IOException,ServletException
{
doGet(rq,rp);
}
}
WEB.xml
<servlet>
<servlet-name>MySqlISNULLFunction</servlet-name>
<servlet-class>MySqlISNULLFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>MySqlISNULLFunction</servlet-name>
<url-pattern>/MySqlISNULLFunction</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular